The present invention concerns a prechamber spark plug for igniting a fuel-air mixture in an internal combustion engine, in particular a gas engine, with a spark plug body comprising a prechamber and a cap that closes the prechamber at least partially, with at least one ground electrode and a central electrode isolated from the ground electrode and projecting into the prechamber.
Prechamber spark plugs of the type in question are known from practice. Prechamber spark plugs are special spark plugs for internal combustion engines, which function in accordance with the principle of lean combustion. Prechamber spark plugs exhibit a prechamber that interacts with the combustion chamber of an internal combustion engine via transfer openings. The fuel-air mixture is ignited by an ignition spark in the prechamber, after which combustion proceeds through the transfer openings into the combustion chamber of the internal combustion engine in the form of ignition flares and there ignites the tendentially reluctant to ignite lean mixture.
A prechamber spark plug is known, for example from WO 2007/092972 A1. This spark plug comprises a prechamber provided with a prechamber wall 2 and a cover surface 8. The prechamber wall 2 comprises a cylindrical part 19, to which rectangular ground electrodes 14 are attached by means of likewise rectangular ground electrode carriers 13. Rectangular central electrodes 12, which are attached to a centric central electrode carrier 11, are associated with the ground electrodes 14. Several pairs of ignition surfaces are thus created, with which ignition that is as centralized as possible in relation to the prechamber should take place.
The complex design exhibited by the known prechamber spark plugs, however, is problematic. To begin with, a large number of individual parts have to be manufactured, which moreover have to be attached to one another to provide a corresponding prechamber spark plug. In addition, the complexity of manufacturing for the individual parts of the prechamber spark plug is very high. With respect to the ignition, there is the further disadvantage that ignition does not take place in a sufficiently concentrated manner due to the large-scale of the ignition regions, whereby ignition at one pair of ignition surfaces can take place at a variety of locations. An arc-like “to and fro” of the ignition spark on one pair of ignition surfaces can occur as well.